Open angle glaucoma exists when the pressure in the eye is not tolerated by the patient and is causing damage to the optic nerve. The current treatment for open angle glaucoma is aimed at reducing the intraocular pressure to a level that is safe for the patient's eye, to preserve vision.
Open angle glaucoma is treated with pharmaceutical agents. Another method of treatment, laser treatment for open angle glaucoma, has been reserved for medical treatment failures but is gaining some favor as a primary treatment. Another approach, intraocular surgery, is reserved for medical and/or laser failures.
Frequently, the increased pressure in the eye is caused by a blockage in the ability of the fluid to leave the eye, not an actual increase of the fluid itself. As shown in FIG. 1, the blockage is typically in the part of the trabecular meshwork near Schlemm's canal, called the juxtacanalicular meshwork. The meshwork is typically blocked by anatomical changes, pigment, extracellular matrix debris or pseudoexfoliative material.
Medical treatment is directed at decreasing the production of the fluid (aqueous humor) or enhancing the ability of the fluid to leave the eye. Medical treatment is not curative. It is used on a continuing basis to decrease the pressure. But, when the treatment is stopped the pressure rises. Also, medical treatment demands patient compliance, has unwanted side effects, is expensive, and may interact poorly with other medical care for the patient.
Laser treatment has been partially successful in its original (argon) method. Newer laser treatment, such as selective laser trabeculoplasty, is gaining favor. However, laser treatment is performed on the inside of the eye and treats the inner, not the outer, trabecular meshwork. With this treatment, there is a secondary physiologic response that causes cells to remove some debris after the laser is performed.
Frequently, after modern day cataract surgery there is a decrease in the intraocular pressure as an unintended positive side effect. When the lens is removed there is more space in the front of the eye. Typical modern cataract surgery removes the cataract by ultrasonic emulsification of the lens material. This method is known as phacoemulsification. Older cataract surgery, without implants, removed more material from inside the eye, but the decrease in intraocular pressure was not as consistent as with modern day or current surgery. It is believed that the ultrasound used to break up the lens material helps dislodge the built up material. However, this is just a side effect, and, as described below, the ultrasonic energy used in phacoemulsification is intense enough to damage tissue.
Accordingly, a need exists for a treatment of glaucoma that includes a method of applying ultrasonic energy to the eye to dislodge built up material and initiate biochemical processes to reduce and remove extracellular debris, thereby decrease pressure, and that can be performed without damaging tissue.